My invention relates generally to apparatus having a transducer such as a magnetic read/write head for data transfer with a disklike record medium such as a flexible magnetic disk, with the transducer transported radially of the record medium by a positioning mechanism including a lead screw. More specifically, my invention pertains to improved means in such data transfer apparatus for easy, precise adjustment, at the time of the assemblage of the apparatus, of the longitudinal position of the lead screw with respect to the radial position of the transducer on the record medium.
In apparatus for data transfer (writing and/or reading) with flexible magnetic disks, a head positioning mechanism is employed for moving the magnetic head radially of the magnetic disk across a series of concentric storage tracks thereon. Typically, the head positioning mechanism comprises a stepper motor and a mechanism for translating the bidirectional, incremental rotation of the stepper motor into the linear, stepwise travel of a carriage carrying the magnetic head. While a variety of motion translating mechanisms have been suggested and used, perhaps the most widely accepted in the art is a lead screw which is coupled directly to the stepper motor and which is matingly engaged with the head carriage either directly or via suitable means mounted to the carriage. U.S. Pat. No. 4,030,137 to Dalziel suggests an example of lead screw for use in the head positioning art.
One of the problems heretofore encountered in the use of lead screws for head positioning is how to obtain exact alignment, at the time of the manufacture or assemblage of the apparatus, between the longitudinal position of the lead screw relative to the head carriage and the position of the magnetic head on a preassigned track on the magnetic disk. The longitudinal position of the lead screw must be determined relative to the head carriage with the rotor of the stepping motor, and therefore of the lead screw itself, held in a prescribed start position, in order that the magnetic head may move to a desired track position on the magnetic disk upon stepping of the motor a required number of times.
Usually, the longitudinal position of the lead screw is adjusted with respect to the radial position of the magnetic head on the magnetic disk by manually moving the assembly of the lead screw and the stepping motor back and forth relative to the head carriage before the motor-and-lead-screw assembly is screwed fast to the framework of the data transfer apparatus. However, no matter how precisely such manual adjustment is made, misalignment has been prone to occur upon full tightening of the screws because of the resulting possible displacement of the motor-and-lead-screw assembly with respect to the framework.